Stephen l



Patented May 27, 1924.

UNITED STATES STEPHEN L. TINGLEY, or NEWYORK, N. Y.

NITROGEN FIXAT'ION.

No Drawing.

To all whom it may concern:

Be it known that I, STEPHEN L. TINGLEY, a citizen of the United States,residing in New York, in the county of New York and the State of NewYork, have invented cer tain new and useful Improvements in NitrogenFixation, of which the following is a specification.

The invention relates primarily to a method of producing ammonia, butmay be applied with equal success to various other gases capable offorming simple compounds, and which it is desired to bring into chemicalcombination, and the reactions may be brought about in a more completeand simple manner than has heretofore been known.

With these and other objects in view the invention consists in the novelsteps and combination ofsteps constituting the process, and in the novelmethod of applying the reactions, all as will be more fully hereinafterdisclosed and particularly pointed out in the claims.

As an illustration of this process when applied to the production ofammonia, three volumes of hydrogen and one volume of nitrogen may bebubbled, after a thorough mixing, through a liquid metal catalystconsisting of a combination of mercury and either-osmium or iron, undera pressure of less than 200 atmospheres and at a temperature below theboiling point of mercury.

As but a relatively small percentage of the gases combine in eachpassage through i the catalyst, it is necessary to continuouslycirculate them, removing at the same time the ammonia formed andreplacing it with fresh nitrogen and hydrogen. There are many methods ofabstracting the ammonia, but, probably the simplest is by refrigerationwhil maintaining the pressure uniform throughout the heated and thecooled zones. The ammonia easily liqueiies and may be drawn off withoutmaterially disturbing the pressure conditions. Another method consistsin absorbing the ammonia in concentrated sulphuric acid, through whichthe slightly cooled gases are passed. In this case great care is neededto avoid introducing the acid or vapors from it, into the catalystchamber.

Although in the above illustration I employ mercury, many other metalsare adapt- .ed for the work, roviding always that at the temperature oftreatment, they are in Application filed December 23, 1921. Serial No.524,481.

the liquid state, and remain in a fluid conin the sense that the mass isin a fluid condi tion. I refer particularly to cases where metal powdersare possessed of strong cat-alytic properties, while their alloys aremuch weaker in this respect. It is possible in many cases to incorporatethem in a liquid metal without causing them to enter into a chemicalcombination.

Some metal powders are capable of absorbing very large volumes ofcertain gases, and this gaseous condensation and absorption reduces agas to an almost nascent state. This probably explains the increasedchemical activity observable in manymethods of applyingthe process. Incases such as the above in which the liquid metal mechanically carries acatalyst, as a suspended catalytic powder,the liquid metal is a truevehicle. This also applies but perhaps in a more narrow xsense where theliquid metal is alloyed with one or more other metals.

Iron, which is an excellent catalyst in the production of ammonia, actsvery peculiarly with mercury. While it is most diflicult to produce whatmight be termed a true amalgam, it is extremely easy to obtain a finealmost colloidal suspension of iron powder in mercury. In fact the ironis in such fine state of division that it may be squeezed throughchamois with the mercury.

As mercury is the most common element of pronounced and undisputedmetallic nature, which is liquid both at low and comparatively hightemperatures, it is frequently employed as the vehicle for carryingmetallic catalysts such as osmium, iridium, platinum, iron, uranium,nickel, etc., as well as the less known catalysts. The metalliccombinations of mercury found to possess the greatest activity and atthe same time remain in the fluid state, are the, ones usually employedfor this purpose. A very large number of elements unite with mercury atordinary temperatures, and others unite by electrolysis and ordinarydouble decomposition to form what are termedamalgains. As examples ofthese may be mentioned barium, bismuth, cadmium, caesium, chromium,cobalt, gold, iron, lead, magnesium, manganese, nickel, osmium,palladium, platinum, silver, sodium, lithium, thallium, tin, zinc,thorium, arsenic, antimony, etc.

Of the many and varied advantages consequent upon the employment of aliquid catalyst, one of the most important is the decidedsurface-freshening induced by the movement of the gases through themass. In this way every bubble is brought in contact with a freshmetallic surface throughout its whole path. I

It is well known that catalysts in the powder form, or deposited in thinlayers on porous surfaces, tend rapidly to become chemically inactiveowing to the formation of a thin coating or scum on the surface, or thedeleterious action of poisons. This is not the case in liquids.

As liquid metal catalysts are splendid conductors and also transmit heatby convection, they are very valuable as temperature regulators. It isoften advisable to maintain the temperature of the incoming gasthroughout the reaction Zone. This is very difficult where the reactionis strongly exothermic, and the surface of the gas and catalyst incontact become highly heated, especially as the porous base mostcommonly used for holding catalysts, is usually an insulating materialsuch as asbestos, and can =hicle is very complete no matter Whether itis removing excess heat from the reaction zone or carrying heat to it.

as would otherwise be the case.

The word vehicle must not be understood to refer to a non-catalyst metalamalgamated or otherwise associated witlrthe catalyst metal, as it has abroader meaning and may or may not be a catalyst itself.

On account ofthe great range of temperature permissible in this process,and the fact that a high temperature is always advisable and in mostcases necessary to .cut down the time, metals that are never classed asliquids may so act in this case. Another advantageous feature is thelowering of the melting point brought about by alloying metals, which ismost pronounced in the case of the so called fusible alloys. spect thereare two limiting features, the temperatur must not be raised above thepoint at which ammonia decomposes into its elements nitrogen andhydrogen, otherwise the reverse action is set up;

In high pressure and temperature work the containing vessels have to beconstructed to withstand unusually hard conditions, and the units cannotbe safely made as large catalyst takes up the least possible space, andin addition may be withdrawn by sim ply opening a tap. At the same timefresh catalytic material may be introduced.

In one re- A liquid 1 It is obvious that those skilled in the art -mayvary the details of the process without departing from the spirit of theinvention, and therefore I do not wish to be limited to the abovedisclosures except as may be re-

